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The rate of reaction between two reactants A and B decreases by a factor of 4 if the concentration of reactant B is doubled. The order of this reaction with respect to reactant B is:[2005]
  • a)
    2
  • b)
    -2
  • c)
    1
  • d)
    -1
Correct answer is option 'B'. Can you explain this answer?
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The rate of reaction between two reactants A and B decreases by a fact...
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The rate of reaction between two reactants A and B decreases by a fact...
Understanding the Reaction Rate
The rate of a chemical reaction can be expressed using the rate law, which is determined by the concentrations of the reactants and their respective orders. For a reaction involving reactants A and B, the rate can be represented as:
Rate = k [A]^m [B]^n
Where:
- k = rate constant
- [A] = concentration of reactant A
- [B] = concentration of reactant B
- m = order with respect to A
- n = order with respect to B
Effect of Doubling Concentration
According to the problem, when the concentration of B is doubled, the rate of reaction decreases by a factor of 4. This means:
New Rate = Rate / 4 when [B] is changed to 2[B]
Mathematical Representation
Let’s set the original rate when [B] is at its original concentration:
Original Rate = k [A]^m [B]^n
When the concentration of B is doubled, the new rate will be:
New Rate = k [A]^m (2[B])^n = k [A]^m (2^n [B]^n) = 2^n * k [A]^m [B]^n
Setting these equal according to the problem:
2^n * (Original Rate) = (Original Rate) / 4
Solving for n
Cancelling the original rate from both sides, we get:
2^n = 1/4
This can be rewritten as:
2^n = 2^(-2)
Thus, n = -2.
Conclusion
The order of the reaction with respect to reactant B is -2, indicating that increasing the concentration of B leads to a significant decrease in the reaction rate. Hence, the correct answer is option 'b) -2'.
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Community Answer
The rate of reaction between two reactants A and B decreases by a fact...
Yes B is correct
here is simple trick
rate of reaction is decreasing thus ans will be in - ve . now,
w.r.t. B -
if conc. of B is double the rate of reaction becomes 4 (means 2 times)
thus ans. is -2
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The rate of reaction between two reactants A and B decreases by a factor of 4 if the concentration of reactant B is doubled. The order of this reaction with respect to reactant B is:[2005]a)2b)-2c)1d)-1Correct answer is option 'B'. Can you explain this answer?
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